1. Field of the Invention
This invention relates generally to systems and methods of manufacturing and, more particularly, to systems and methods of determining a defect source manifested by localized elevation on the surface topography of a semiconductor substrate.
2. Description of Related Art
As the physical dimensions of semiconductor devices continue to decrease, the topography of the semiconductor substrate upon which the integrated circuit devices are formed becomes an important factor. A semiconductor processing step such as photolithography is used to pattern images in a photoresist on the surface of the substrate. The quality of the images formed on the surface of the substrate by photolithography is related to the topography of the substrate since the topography of the substrate can affect the focus of the photolithographic tool. Localized areas of relatively high elevation can result in defocusing of the patterned images in “hotspots”.
Hotspots are typically caused by a defect source such as foreign particulate matter trapped between the substrate and the photolithography aligner chuck upon which the substrate is placed. The foreign particulate matter causes the substrate to bend or deflect resulting in an elevation of a portion of the surface of the substrate above the foreign material. When the elevation deviation is large enough, the imaging surface will be out of focus relative to surrounding images, and imaging failure occurs typically resulting in a nonfunctioning semiconductor device.
When a hotspot is detected, unnecessary maintenance activity may be performed on the chuck when the defect is actually on the incoming substrates.